In order to produce a disc rotor motor with reduced material costs, the prior art (author: Sone, Kodai; et. al., title: “A Ferrite PM In-Wheel Motor Without Rare Earth Materials,” IEEE Transactions on Magnetics, 48(11): 2961-2964) has disclosed equipping a rotor embodied as a rotor disc exclusively with ferrite magnets in order to thus produce the permanent magnetic poles for torque production. It is therefore possible to avoid the need for permanent magnets made of rare earth, which in addition to reduced costs, also results in disc rotor motors with comparatively low eddy current losses. The rotor, as is customary in disc rotor motors, is oriented parallel to the stator and is spaced apart from the stator by an axial gap. The stator yoke of the stator is made of a soft magnetic powdered composite and forms stator teeth with wound, stub-ended tooth necks. The disadvantages of using inexpensive ferrite magnets are that on the one hand, reduced power densities and on the other, lower torque densities are to be expected. Increased diameters of the rotor disc can in fact compensate for this—but they increase the overall size with regard to the motor diameter, which is comparatively large anyway due to this motor concept. If the amount of available installation space is small, which is one of the challenges, for example, in automotive engineering, then such comparatively inexpensive, but large disc rotor motors are unsuitable.
The object of the invention, therefore, is to modify the design of a disc rotor motor of the type mentioned at the beginning so that despite the ferrite magnets on the rotor, a high power and torque density can be achieved and in addition, small motor dimensions can be maintained in order to permit an installation in a cramped installation space. In addition, the disc rotor motor should have a low weight.